Improvement in propellers



y a ALEXANDER o. MARSHALL,

or' wAnnnNroN, VIRGINIA.'

Letters Patent Na. 112,366, dated umh' 7, 1871; mitad March e, 1871. i

IMPROVEMENT IN PROPELLERS.y

The Schedule referred tou theseI Letters Patent and making prt of thesame.

, I, ALnXA'nnnR J.-`MAns`HALL, of Warrenton, in the county of Fauquierand State of Virginia, have invented' certain Improvements in theApplication' of Steamflower to -thePropulsion of Boats upon the WatersofCanals .as well Aas upon-,other waters, of which thefollowng isaspeciication. 1

Nature and Olyeotsvof the Intention.

The iirst part of my invention relates tothe form, l to the mounting,and to the operation of the paddles Por propellers of boats, iu' such amanner that theysvhall present theiwrilat` or .concavesurfaces and shallbe driven by the'force of steam directly in right lines against-thewater in the rear of the boat, and that allel to, the4 surface, andyetso far below it, that it shall not`-be greatly agitated by' theirmotion, while the water Where the propellersdooperate will have itspower of resistance to, them vgreatly increased by' theweight of thewaterjaboveit; and furthermore, .Q

that the propellers shall be driven againstthe water alternately, sothat, while lone is driven as aforesaid, @the other shallbe-withdrawnedgewise.

The second part of 'my invention relates to the construction, location,and arrangement of thesteam cylinders in the stern of the boat, in sucha manner that the paddlesor propellers shalleach. be hinged upon a`frame which shallbe fastened upon the outerV end of a plunger,'whichismerely an elongation of the piston, and be driven and withdrawn by itwithout any intermediate Inachinery. L l

` Description ofthe Accompanying Drawing.

g Figurel is a ground-planlof the rear section of a boat with myimprovements shown in it.

y 1 Figure 2 `is 'adongitudinal vertical Vsection of the same.

ton, paddle, andthe frame in, which it is mounted.

1 General Description. v The letters AA A indicate the sides and O thesternproper of the boat,"and K thebottoin, and the part-i` tion C andthe sides AA` exten led, together with li, constitute a second ,or falsestern, which isprovided niei'el y to protect the paddles or propellersfrom injury j 'or obstruction such as may be caused hy dritt or by.coming in contact with the banks, the gates of locks, and the like.This false stern isplanked up from bei low the surface of `the water, so"the true stern, and should be suilicientlystrong to serve the purposedesigned.

The guides II their fhrward ends bolted down upon the cross-timbersM'Maiter passing throughthe partition O, and are thus h eld rividlyinposition,

they shall be so driven against the water in lines par-.y

Figure?) is a detached view, in perspective, of a pisas to appearto heand extend to the openings o r, between the end piece B, and O 0 thebrace for the sides -of the -outer stern. .l The outside guides areprovided with beveled edges on their inner sides, and the middle guideis provided.

with `like edges on both its sides to fit the grooves ff v in thecross-heads F F. These guides and cross-heads, should be made 'of metalof sujcient hardness and tremities, and the paddle-braces H H should belet into the cross-head or cast together with it in one piece, so thattheir outer surfaces. shall be flush with each other, to the end thatwhen the paddles G G are' driven against the waterl there shall be anequal pressnre against both, and the center of each paddle should abut`against thefcenter of each plunger.

The uprights HH should have the form shown in figs. 2 and 3. The parts',-HI' act as stops to prevent the lower ends ofthe paddles from beingthrown bythe action of thewater, or otherwise, quite as high 4' as thelupper ends';` 'orit' Ithe lower edges were to be raised higher than.the upper, it, might be thrown` upward A instead of downward when itsplunger was forced outward against the water.

.The paddles should be made of metal, of theform, or about the form,shown in' the drawing. The pins upon which the paddles turn in the upperparts'oi` the,

. braces maybe in one piece with the 'paddle itself', or

otherwise.

In g. 2, G is the paddle in position to Vloe' driven` against the water,and in iig.A 3 the same' letter indicates the paddle as being withdrawnedgewise by the plunger.

`Asa certain means of inducingthe -outer end of the paddle to be throwndown instead of up, the lower and outer edge mightbe in the beveledformshown 'in iig. 3, Its own weight, however, will` always tend to r giveit adownward inclination.

The steam-cylindersv D D 'maybe imbedded in timbers, in any lsuitablemanner, in the boat.l

As to'the location of the-boiler in which the steam is to be generated,and the 1mechanical contrivances by which the steam isto be so appliedas to draw out and draw in the pistonsE E alternately, these things maybe done'in many dilerent ways, and I do not herein make any claim for`any-of` them.

In the drawing the pistons are provided with` stuffing-boxes Where theypass through Vthe partition or ,bulkhead Unas shown at L, iig. 2, toprevent the admission of water `into the boat.- Y i Itwill appearin thedrawing that the steam-'cylinders are placed with their back endsagainst the partition C, and it is obvious, therefore, that when apiston is driven out against the water a portion of it will bein-contaot with and be cooled in some degree by .the water, and that,when again it enters its cylinder,

it will condense the steam therein to some extent. That result may beeasily avoided by placing the cylinder so much further forward in theboat that no portion of the piston which will come in contact with thewater will reach it.

I have not attempted in this specification to give the dimensions or theproportions of the various parts to each other. They should, of course,be varied according to the conditions and circumstances existing whenand where my improvements are used.

1 will suggest; however, that the lower edges of the paddles should, inthe outward'push against the water, move in a line but a few inchesabove that of the bottom of the boat, for the reason that the furtherthey operate below the surface the greater will be the resistance of thewater and the less will it be thrown into waves upon the surface, andthe less will be the injury done to the banks of canals and other bodieso f water.

These improvements are especially designed for the propulsion of boatsupon the waters of canals, but it is believed that their use will befound expedient upon lakes and rivers also.

It is obvious that my prol 1ers or paddles may be` operated by animal orother power as well as that of steam, and that any number of them may beused to propel a single boat.

I do not claim to be the first inventor of a propeller to be driven backin a right line with the line of direction of the boat to be propelledagainst the water in the rear of the same, nor of the described mode ofconnecting the propeller immediately with the piston of a steam-cylinderlocated inthe boat; but

(lo claim- The paddle G, formed and hinged as shown, and its cross-headF, the uprights H H, with their projections H H and their grooves ff,when each is constructed and all are arranged and combined substantiallyas and for the purpose described.

A. J. MARSHALL.

Witnesses O. J. Heumen, A. M.- STOUT, Jr.

